S: Dinosaurs and Fossils
FC: Dinosaurs and Fossils | By: Allison Keener, Josh Mitchell, & Waleed Ali
1: DINOSAURS AND FOSSILS by: Allison Keener, Josh Mitchell, and Waleed Ali
2: To Zambia
3: Notes from the authors | Dear Readers, Hi there! I'm Allison! I'm fifteen years old and I am in the tenth grade. I love to dance. I also love to read. When I was told that we were making books to send to Zambia I was beyond excited. I want to be a teacher when I grow up so being able to share knowledge with kids is what I love. I really hope you enjoy reading about dinosaurs! With Love, Allison | Allow me to introduce myself, my name is Josh and I'm very excited to be able to help make this book. I attend Siegel High School and I'm a fifteen year old musician. I play the drums, guitar, and piano. I hope you enjoy our book as much as we enjoyed writing it! | Hello! My name is Waleed. I'm 16 years old and in the 10th grade. I love playing all kinds of sports like basketball and American football. I am also a big reader. When I found out we were writing books for Zambia, I was very excited. I knew I was going to have a good time writing, and I also learned a lot while writing this book too! I hope you enjoy and learn as much as I did! Have fun, Waleed
4: Introduction to Dinosaurs
5: They are easily the largest animals that have ever walked on this earth. They lived so long ago, but were still able to adapt to their environment. We have never seen them in real life, yet we know so much about them. They are dinosaurs – some of the most fearsome creatures the earth has ever seen – and they still amaze us to this day. These reptiles could range from “chicken-like carnivores” weighing 5-6 pounds (2-3 kg) all the way to huge lizards that reached up to 80 tons (73 metric tons) (“dinosaur” 1). Throughout this book, we will see the differences between different types of dinosaurs, theories of why they disappeared so quickly, and how we have been able to use their bones to find out so much about their lives. This isn’t just science – it is discovery!
6: “The word ‘dinosaur’ is derived from two Greek words, meaning terrible lizard” (“dinosaur” 1). This term was coined by a Victorian anatomist named Sir Richard Owen (1). While dinosaurs do not coexist with humans, we still know much about how they lived and thrived during their lives. “The dinosaurs arose during the time known as the Mesozoic (Middle Life) Era, often called the ‘Golden Age of Reptiles’ or ‘Age of the Dinosaurs’” (“dinosaur” 1). The reason that it is called this is because during the Mesozoic Era, a time from about 250 to 65 million years ago, dinosaurs were the dominant species (1). You will learn more about the Mesozoic Era in the next section. Dinosaurs were able to be set apart from others because of their behavior, physiology, and ecological relationships. But, not much is known about these traits, and one of the only ways to get knowledge about dinosaurs is studying their fossil remains and their diet.
7: DIET Everyone has to eat, right? This is also true for the dinosaurs, even though they did not all eat the same things. While “some dinosaurs were fierce predators, others were mild-mannered herbivores” (“dinosaur” 1). A predator is an animal that hunts other animals for their meat, and an herbivore eats plants. While bipedal dinosaurs were usually predatory, tetra pods mostly herbivores. 65% of dinosaurs ate plants, and 35% were carnivores, or meat eaters (Col 1). To represent the flow of food throughout the ecosystem of the dinosaurs, the diet could be represented by a pyramid. There would be more plants than herbivores, because it takes a lot of plants to satisfy them. The same is said for carnivores; they need a lot of meat, so there must be many herbivores for them to eat. This is a basic idea of a food chain. There have to be more organisms in the lower levels so that energy can flow properly throughout the food chain (Col 1).
8: Herbivores had to eat a lot of plants. Because plants are low in calories, herbivores would have to consume much more than carnivores do to stay healthy (Col 2). Some herbivores were even able to store food in their cheeks! (2). If you looked at the teeth of an herbivore, it would have blunt teeth, which were used to rip the leaves or twigs off of trees, or grass off the ground. Also, some herbivores would have flat teeth so that they could “grind tough plant fibers” (2). In addition, to digest these fibers, a strong digestive system was needed, which was seen in these types of dinosaurs (2). Still, it was not certain exactly what a certain herbivore’s individual diet was, besides the fact that it was all plants. “All you can do is guess a dinosaur’s diet based on the type of teeth it had, where it lived, and what plants were around during the time period” (3).
9: If all the plants were gone, what would the carnivores eat? The plant eaters. The carnivores’ diet consisted of other animals, whether it was herbivores, or other carnivores. “[They] usually had long, strong legs so that they could quickly catch their prey. They also needed large, strong jaws, sharp teeth, and deadly claws to kill and rip apart the prey” (Col 3). Unfortunately, though, the carnivores’ food did not wait for them like plants did for herbivores; they had to hunt, which was not easy for dinosaurs. It was something that needed skill and planning. “Good eyesight, a keen sense of smell, and a large brain to plan hunting strategies [were] very important for successful hunting” (Col 3).
10: Just like in any other food chain, “equilibrium” was made. When carnivores eat more herbivores, the plant eating community decreases. When there are less herbivores, many carnivores are left without food, decreasing the meat eating population (Col 1). Cycles like these maintain the balance between herbivores and carnivores, and herbivores and plants. | As we can see, dinosaurs showed us their dominance while they were alive. But where and why did they go? Read the next section to find out!
11: End of Section Review: 1. What time period did dinosaurs live in? 2. One way to find out about dinosaurs is studying fossils. What is another thing to study? 3. What are herbivores and carnivores? 4. Name at least two physical features an herbivore would probably have. 5.Name at least two physical features a carnivore would probably have. | Answers: 1. Mesozoic Era (250-65 million years ago). 2.Their diet 3.Herbivores - plant eaters Carnivores - meat eaters 4. Blunt or flat teeth, strong digestive system, pouches for storing food, etc. 5. Strong legs, strong jaws, sharp teeth, deadly claws, etc.
12: Time Periods & Where did the Dinosaurs go?
13: Time Periods | As you have learned, dinosaurs lived a very long time ago. This time was called the Mesozoic era (Barrett 14). During this era there were three distinct periods. | Triassic | The first period is the Triassic. "It lasted from about 245 to 213 million years ago" (14). The earth was also very different. "[It] was relatively dry at the time and was covered with deserts" (14). With large deserts there weren't many plants, therefore there were not many herbivores during this time. The earth's continents were also different. All of the continents were together on one large landmass called Pangea (14).
14: Jurassic | The next period was the Jurassic. It lasted from 213 to 144 million years ago (14). This was also the time the earth became more wet and different dinosaurs started to appear. Large carnivores also started to appear. In result of these carnivores, dinosaurs started to develop armor (14). Also during the Jurassic period, "the continents started to break apart from each other" (14). | Cretaceous | The last period in the Mesozoic era was the Cretaceous period. This period lasted from 144 to 65 million years ago (14). Some of the most famous dinosaurs appeared during this time, such as the Tyrannosaurus Rex and the Triceratops (14). However, the close of the Cretaceous period marks the end of the age of dinosaurs" (14). | Triceratops Model (Piper).
15: Where did the dinosaurs go? | There are many theories on why the dinosaurs went extinct. Some have less evidence than others. One unlikely theory was that mammals ate all of the dinosaur eggs, but that would require a large number of mammal that were not present (Barrett 182). Another unproven theory was that the large dinosaurs with small brains couldn't adapt or compete with smaller animals (Trexler). Some also believe that caterpillars were the cause of extinction. Caterpillars evolved in the late Cretaceous period. The caterpillars stripped the plants of their leaves, leaving nothing for the herbivores to eat. Which then killed the herbivores, leading to the death of omnivores and carnivores (14). | To the left, a caterpillar. Caterpillars are one of the unproven theories of why the dinosaurs went extinct.
16: Comet | The most popular theory is that a comet landed and destroyed the dinosaurs. Walter Alvarez came upon this discovery by surprise. "he found that a certain narrow layer of rock contained some 25 more time as much rare metal iridium as there was above and below it" ("Alvarez"). Only an asteroid could put that much iridium into the earth. "Alvarez postulated, that a large asteroid or comet several miles across has struck the earth 65 million years ago ("Extinction"). This asteroid was the size of San Francisco, and traveled faster than a bullet ("Alvarez"). The crater that this information was found was soon named the Chicxulub Crater. It was 10 kilometers wide and just off the northeast coast of the Yucatan Pennisula (Trexler). From Alvarez's findings, he "conclude[d] that the Chicxulub impact was the ultimate cause for the extinction of dinosaurs" ("Extinction"). | Disease | Disease is also a popular belief on why the dinosaurs went extinct. As the earth got hotter during the Cretaceous period more land bridges started to appear on earth (Trexler). Of course, the dinosaurs were curious of these land bridges and where they led to. However, the "land bridges brought more dinosaurs looking for food into the new land. They brought all of the disease that those dinosaurs had inside them" (Trexler). There dinosaurs were already immune to these diseases, "but to the other dinosaurs they [were] fatal" (Trexler).
17: Section Review | 1. Did the Cretaceous period or the Triassic period come first? 2. What period did the dinosaurs go extinct during? 3. Name three theories on why the dinosaurs went extinct. 4. Where is the Chicxulub Crater located? 5. How long ago was the Jurassic Period? | Answers | 1. Triassic. 2. Cretaceous 3. Possible Answers: Chicxulub Comet, Disease, Caterpillars, overpopulation of mammals 4. Yucatan Pennisula 5. 213 to 144 million years ago
18: How do we know about dinosaurs today?
19: If you are traveling through a forest, how would someone be able to know that you have been through there? Well, There would be broken sticks, rustled leaves, foot prints, maybe left over food or scraps. Eventually, if your foot print was left untouched, sediment would fill in the foot print and soil would build up and compress the sediment in the print to make a fossil, a trace fossil to be exact. You may ask, “what is a fossil?” Well, “fossils are the recognizable remains of organisms that once lived and include bones, shells, leaves, and indirect trace fossil evidence such as tooth makes, tracks, burrows, nests, eggs, and impressions” (Powell1). | Fossils have been found all over the world for probably thousands of years; some cultures believed them to be bones of “dragons” (“First”). | Introduction | Fun Fact
20: There are several different kinds of fossils: mold fossils, cast fossils, trace fossils, and true-form fossils. Most dinosaur bones are true-form fossils. The first dinosaur bone was actually found in 1676 in England, this bone was thought to be the bone of a “giant” but it was certainly a bone of a dinosaur (“First”). | Fossil Types | Example of a mold fossil. A mold fossil is formed by the impression left in rock by the remains of an organism. | Example of a cast fossil. A cast fossil occurs when the mold is filled in by precipitating minerals. | Example of a trace fossil. Marks left in sediment left by the organism.
21: Who finds the dinosaur bones and researches them? Well, paleontologists do this. “Paleontology, is the study of fossils and past geologic time periods” (Powell 1). Fossils have been able to provide information from a time where humans weren't present; “[they] actually record more than six million years of history” (Powell1). | The Experts
22: It may be hard to believe, but a lot has actually changed over time, and you may be curious as to what fossils can tell us about the past. Fossils help paleontologists hypothesize how the Earth used to look, how animals have evolved, the change of climate, and what animals have gone extinct (Powell 1).For example, in Africa experts have discovered that the Sahara desert used to contain vast amounts of water. They know this because of the several discoveries of dinosaurs around that area that fed and lived in water (Reed 1). What exactly may these fossils tell us? Fossils such as teeth or claws tell us if a certain dinosaur is a carnivore, herbivore, or omnivore, and trace fossils such as tracks can tell us how fast this dinosaur travels and its stalking behavior (Types). Where are dinosaur fossils found? Dinosaur fossils are mostly found in sedimentary rock like limestone, sandstone, claystone, etc. (Powell 1). Researchers typically look for fossils in quarries, mountainsides, and typically anywhere that contains lots of exposed sedimentary rock.
23: These fossils give desired information on extinct species, or animals that are no longer around because the climate changed and there weren't able to adapt fast enough, thus depleting the population of that certain specimen (Powell 6). Who knows, maybe one day people will be looking at fossils of us? | What did you learn? | 1. What is a fossil? 2. Why do experts know that the Sahara desert once contained vast amounts of water? 3. What is the difference between a cast fossil and a mold fossil? 4. What does a paleontologist do? 5. What kind of rock are fossils mostly found in? | 1. A fossil is the recognizable remain of an organism that once lived. 2. They found dinosaur remains that indicate that they lived in water. 3. A cast fossil is where minerals fill in the mold of an organism, a mold is simply where the organism's remains leave an indention in the sediment. 4. A paleontologist studies fossils and past geologic time periods. 5. Fossils are typically found in sedimentary rock, but they can be found in other rock types as well. | Answers
24: Glossary Bipedal- any organism that walks upon two legs, such as a human or bird Carnivore- meat eater Coexist- to exist at the same time Comet- a celestial body moving about the sun, usually in a highly eccentric orbit, consisting of a central mass surrounded by an envelope of dust and gas that may form a tail that streams away from the sun. Compress- to pack tightly Continent- one of the main landmasses of the globe Crater- a hole in the Earth Deplete- to erase the supply Dinosaur- Word derived from the Greek language that means, "terrible + lizard" Dominant- Superior Equilibrium- a state of rest or balance due to the equal action of opposing forces Era- a period of time marked by distinctive character, events, etc. Evolve- to change Extinction- to completely die out, referring to an entire species Herbivore- plant eater Hypothesize- to make an educated guess Mesozoic Era - era of time, (Middle Era), when dinosaurs were dominant
25: Paleontologist- one who studies paleontology Predators- any organism that survives by preying, or hunting, on other organisms to survive Sediment- mineral or organic matter deposited by water, air, or ice. Tetra pods- organism that walks on four legs Theory- a proposed explanation whose status is still conjectural, in contrast to well-established propositions that are regarded as reporting matters of actual fact. Trace Fossil- a fossil made by a trace left on the ground | works cited for dictionary Dictionary.com | Free Online Dictionary for English Definitions. Web. 03 Apr. 2011.
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